1. Technical Field
The present disclosure relates to an image capturing apparatus. More particularly, the present disclosure relates to an image capturing apparatus which is applicable to portable electronic devices.
2. Description of Related Art
In recent years, with the popularity of mobile devices having camera functionalities, the demand of miniaturized optical systems has been increasing. The sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality.
Furthermore, due to the popularity of mobile devices having camera functionalities along with the advanced manufacturing technology of lens elements and sensors, the applicable environments of the optical system can be expanded. However, when the optical system originally applied in air is used in the non-air medium such as water, the refractive power thereof becomes smaller and the back focal length thereof becomes longer. It results in unfavorable optical properties like image defocus as the optical system is used in the non-air medium.
Although the optical system applied in air and in the non-air medium has been developed, the physical size of mobile devices is usually too small for the focusing apparatus, so that it is difficult to solve the image defocus problems of the optical system applied in the non-air medium.